STAT5 transcriptional activation induced by p12^I depends on binding to the IL-2R β chain.

In this experiment, 293T cells were transfected with plasmids expressing IL-2R β, IL-2R γ_c, Jak3, and STAT5b with or without p12^I. IL-2 was added 20 hours later; after 24 hours, activation of the β-casein luciferase reporter was determined by using a luminometer. A Renilla luciferase reporter (Promega, Madison, WI) was used to control transfection efficiency. (A) Basal transcriptional activation of STAT5b in the absence of IL-2. (B) STAT5b activation with increasing amounts of IL-2 (nM). The error bars in panels A, B, and D indicate the SE from 3 independent experiments. Panel C shows a representative experiment. At least 3 independent experiments were done to obtain the results shown in each panel. WT indicates wild-type IL-2R β, and A indicates the βΔA mutant.